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11.
Optical total reflection and transmission with mode control in a dielectric subwavelength nanorod chain 下载免费PDF全文
We report a polarization dependent reflection phenomenon beyond the normal incidence with a subwavelength nanorod chain.Light waves of the transverse electric mode will be totally reflected while those of the transverse magnetic mode will transmit through.The total reflection or transmission phenomenon can be seen as a constructive or destructive interference of the incident field with the transverse mode field of the chain.With the low-loss feature and the ultra-compact characteristic,this structure may find applications in photonic circuits. 相似文献
12.
Improvement of total-dose irradiation hardness of silicon-on-insulator materials by modifying the buried oxide layer with ion implantation 下载免费PDF全文
The hardening of the buried oxide (BOX) layer of separation by implanted
oxygen (SIMOX) silicon-on-insulator (SOI) wafers against total-dose irradiation
was investigated by implanting ions into the BOX layers. The tolerance to
total-dose irradiation of the BOX layers was characterized by the
comparison of the transfer
characteristics of SOI NMOS transistors before and after irradiation to
a total dose of 2.7
Mrad(SiO2. The experimental results show that the implantation of
silicon ions into the BOX layer can improve the tolerance of the BOX layers
to total-dose irradiation. The investigation of the mechanism of the
improvement suggests that the deep electron traps introduced by silicon
implantation play an important role in the remarkable improvement in
radiation hardness of SIMOX SOI wafers. 相似文献
13.
Shortening turn-on delay of SiC light triggered thyristor by7-shaped thin n-base doping profile 下载免费PDF全文
A new 4 H–SiC light triggered thyristor(LTT) with 7-shaped thin n-base doping profile is proposed and simulated using a two-dimensional numerical method. In this new structure, the bottom region of the thin n-base has a graded doping profile to induce an accelerating electric field and compensate for the shortcoming of the double-layer thin n-base structure in transmitting injected holes. In addition, the accelerating electric field can also speed up the transmission of photongenerated carriers during light triggering. As a result, the current gain of the top pnp transistor of the SiC LTT is further increased. According to the TCAD simulations, the turn-on delay time of the SiC LTT decreases by about 91.5% compared with that of previous double-layer thin n-base SiC LTT. The minimum turn-on delay time of the SiC LTT is only 828 ns,when triggered by 100 mW/cm~2 ultraviolet light. Meanwhile, there is only a slight degradation in the forward blocking characteristic. 相似文献
14.
Resistivity and Radio-Frequency Properties of Two-Generation Trap-Rich Silicon-on-Insulator Substrates 下载免费PDF全文
Crystal morphologies and resistivity of polysilicon trap-rich layers of two-generation trap-rich silicon-on-insulator(TR-SOI) substrates are studied. It is found that the resistivity of the trap-rich layer of generation 2(TR-G2)is higher than that of generation 1(TR-G1), although the crystal morphologies of the trap rich layers are the same. In addition, the rf performance of two-generation TR-SOI substrates is investigated by coplanar waveguide lines and inductors. The results show that both the rf loss and the second harmonic distortion of TR-G2 are smaller than those of TR-G1. These results can be attributed to the higher resistivity values of both the trap-rich layer and the high-resistivity silicon(HR-Si) substrate of TR-G2. Moreover, the rf performance of the TR-SOI substrate with thicker buried oxide is slightly better. The second harmonics of various TR-SOI substrates are simulated and evaluated with the harmonic quality factor model as well. It can be predicted that the TR-SOI substrate will see further improvement in rf performance if the resistivities of both the trap-rich layer and HR-Si substrate increase. 相似文献
15.
化学与酶促相结合合成人生长激素基因 总被引:1,自引:0,他引:1
根据人生长激素(hGH)的氨基酸序列和大肠杆菌密码子的偏好性, 全面优化hGH的密码子, 添加表达调控元件后合成序列的全长为1040 bp, 采用化学方法拆分成30条单链寡核苷酸. 采用改进的两步法拼接成全基因, 得到2个全序列正确的基因. DA-PCR和OE-PCR拼接产物经T7核酸内切酶Ⅰ处理, 合成基因中的碱基错误率降低了93.93%. 相似文献
16.
采用乌头碱和人肠内细菌体外温孵的方法, 探讨乌头碱在肠内的生物转化规律. 乌头类生物碱在ESI正离子模式条件下形成质子化分子[M+H]+, 利用离子阱电喷雾串联质谱和傅立叶离子回旋共振电喷雾串联质谱方法可以直接分析乌头碱的转化产物. 本文首次报道了乌头碱在人肠内菌群环境中产生16-O-去甲基乌头碱, 16-O-去甲基乌头碱可进一步被肠内细菌转化, 通过脱乙酰基、脱苯甲酰基、脱甲基、脱羟基以及酯化反应, 产生新型的单酯型、双酯型和20余种脂类生物碱等转化产物. 相似文献
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当结晶聚合物由熔融冷却或从浓溶液中析出结晶时 ,在不存在应力和流动的情况下 ,一般形成球晶 .球晶在一定的生长时期内呈现球形外观 ,在偏光显微镜下通常呈现Maltese黑十字消光图样 .球晶作为一种常见的结晶形态 ,由片晶堆积而成[1,2 ] .Keith和Padden认为形成球晶的体系包含杂质和聚合物链 ,由于杂质在片晶生长界面的富集导致片晶产生小角度分叉 ,这样片晶能填满球状的空间[1,2 ] .近年来的研究表明球晶是由一个片晶开始生长 ,片晶在生长过程中不断的诱导成核使片晶分叉 ,首先形成片晶捆束 ,然后片晶向各个方向发散生长 ,最终形成球晶[3… 相似文献
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